Sensor with inner protective chamber

Abstract

A sensor for sensing a property of a body, such as vibration or knocking of an internal combustion engine. The sensor includes an outer hollow tubular sensor casing, one end of which is open and the other end of which is closed and is provided on its outside with a protuberance adapted for connection to the body; an end closing member which closes the open end of the tubular sensor casing, and which is fixedly mounted to it; a sensor element for producing an electrical output signal, mounted within the tubular sensor casing; a sensor element side protective member, passing all around the sensor element between it and the inner wall of the tubular sensor casing; a sensor element base end protective member, between the sensor element and the second closed end of the tubular sensor casing; the sensor element side protective member and the sensor element base end protective member being coupled together so as to form an assembly receiving the sensor element in a substantially closed chamber; and an electrically conducting sensor lead structure, connected by one of its ends to the sensor element, for receiving a sensor output electrical signal from it, and passing through an aperture in the end closing member to the outside of the sensor.

I claim: 
     
       1. A sensor for sensing a condition of a body, comprising: an outer hollow tubular sensor casing, a first end of which is open and a second end of which is closed and is provided on its outside side with a protuberance adapted for connection to the body;   an end closing member which closes the first open end of the outer hollow tubular sensor casing, and is fixedly mounted thereto;   a sensor element for producing an electrical output signal, mounted within the outer hollow tubular sensor casing;   a sensor element side protective member, passing all around the sensor element between it and the inner wall of the outer hollow tubular sensor casing;   a sensor element base end protective member, between the sensor element and the second closed end of the outer hollow tubular sensor casing;   a sensor element other end protective member defining an end of the substantially closed sensor element protective chamber remote from the second closed end of the outer hollow tubular sensor casing;   the sensor element side protective member, the sensor element base end protective member, and the sensor element other end protective member are formed as separate members, and are all clamped together between the end of the end closing member closest to said second closed end of the outer hollow tubular sensor casing, and the inside side of the second closed end of the outer hollow tubular sensor casing, the side of the end closing member closest to the second closed end abutting the side of the sensor element other end protective member remote from the second closed end, the side of the sensor element other end protective member closest to the second closed end abutting the end of the sensor element side protective member remote from the second closed end, the end of the sensor element side protective member closest to the second closed end abutting the side of the sensor element base end protective member remote from the second closed end, and the side of the sensor element base end protective member closest to the second closed end abutting the inside surface of the second closed end; and   an electrically conducting sensor lead structure, connected at its one end to the sensor element for receiving a sensor output electrical signal therefrom, and passing through an aperture in the end closing member to the outside of the sensor.   
     
     
       2. A sensor according to claim 1, wherein the side of the substantially closed sensor element protective chamber remote from the second closed end of the outer hollow tubular sensor casing is defined by the end closing member. 
     
     
       3. A sensor according to claim 2, wherein the sensor element side protective member is formed integrally with the end closing member. 
     
     
       4. A sensor according to claim 3, wherein the sensor element base end protective member is clamped between the end of the sensor element side protective member remote from the first open end, and the inside side of the second closed end. 
     
     
       5. A sensor according to claim 1, wherein the sensor element other end protective member and the sensor element side protective member are integrally formed as a cup shaped member with its opening facing in the direction of the second closed end of the outer hollow tubular sensor casing, while the sensor element base end protective member is formed separately from the cup shaped member, with the side of the sensor element base end protective member remote from the second closed end abutting the edge of the cup shaped element on its side closest to the second closed end, while the side of the sensor element base end protective member closest to the second closed end abuts the inner surface of the second closed end, the sensor element base end protective member extending laterally beyond the outside of the sensor element side protective member to provide a shelf. 
     
     
       6. A sensor according to claim 5, further comprising a ring shaped member, surrounding the sensor element side protective member, the end of the ring shaped member closest to the second closed end of the outer hollow tubular sensor casing abutting against the side of the shelf remote from the second closed end and clamping the sensor element base end protective member against the inner surface of the second closed end. 
     
     
       7. A sensor according to claim 6, wherein the ring shaped member is integral with the end closing member. 
     
     
       8. A sensor according to claim 6, wherein the ring shaped member is separate from the end closing member, and the end of the ring shape member remote from the second closed end of the outer hollow tubular sensor casing abuts the side of the end closing member closest to the second closed end. 
     
     
       9. A sensor according to claim 7 or claim 8, wherein the electrically conducting sensor lead structure comprises a connector element, whose end remote from the second closed end of the outer hollow tubular sensor casing projects outside from the end closing member, and whose end closest to the second closed end of the outer hollow tubular sensor casing is mounted to the sensor element other end protective member on its side remote from the second closed end. 
     
     
       10. A sensor according to claim 9, wherein the space between the cup shaped element, the sensor element base end protective member, the ring shaped member, and the end closing member is filled with plastic material. 
     
     
       11. A sensor according to claim 9, wherein the part of the connector element between the sensor element other end protective member and the end closing member is sinuous. 
     
     
       12. A sensor according to claim 7 or claim 8, wherein the electrically conducting sensor lead structure comprises a connector element and a clip, the clip being mounted to the side of the sensor element other end protective member remote from the second closed end of the outer hollow tubular sensor casing, the end of the connector element remote from the second closed end projecting outside from the end closing member, while the end of the connector element closest to the second closed end is engaged with the clip. 
     
     
       13. A sensor according to claim 12, wherein the space between the cup shaped element, the sensor element base end protective member, the ring shaped member, and the end closing member is filled with plastic material. 
     
     
       14. A sensor for sensing a condition of a body, comprising: an outer hollow tubular sensor casing, a first end of which is open and a second end of which is closed and is provided on its outside side with a protuberance adapted for connection to the body;   an end closing member which closes the first open end of the outer hollow tubular sensor casing, and is fixedly mounted thereto;   a sensor element for producing an electrical output signal, mounted within the outer hollow tubular sensor casing;   a sensor element side protective member, passing all around the sensor element between it and the inner wall of the outer hollow tubular sensor casing;   a sensor element base end protective member, between the sensor element and the second closed end of the outer hollow tubular sensor casing;   the sensor element side protective member and the sensor element base end protective member being coupled together so as to form an assembly receiving the sensor element in a substantially closed chamber; and   an electrically conducting sensor lead structure, connected at its one end to the sensor element for receiving a sensor output electrical signal therefrom, and passing through an aperture in the end closing member to the outside of the sensor;   the sensor element base end protective member and said sensor element side protective member are integrally formed as a cup-shaped member with its opening facing in the direction away from the second closed end of the outer hollow tubular sensor casing, and further comprising a sensor element other end protective member mounted at an intermediate axial position within the hollow space within the outer hollow tubular sensor casing, the cup-shaped element being attached to the side of the sensor element other end protective member closest to the second open end and the electrically conducting sensor lead structure passing through a hole formed in the sensor element other end protective member.   
     
     
       15. A sensor according to claim 14, further comprising a hollow cylindrical axially slotted bracing ring, which is mounted within the outer hollow tubular sensing casing, and whose outer cylindrical face cooperates closely with an inner cylindrical face of the outer hollow tubular sensor casing, the axial end of the hollow cylindrical slotted bracing ring more remote from the second closed end closely abutting the side of the end closing member closest to the second closed end, and the end of the hollow cylindrical slotted bracing ring closer to the closed second end closely abutting the side of the sensor element other end protective member remote from the second closed end, while the side of the sensor element other end protective member closest to the second closed end abuts a step formed in the inner cylindrical surface of the outer hollow tubular sensor casing. 
     
     
       16. A sensor for sensing vibration of a body, comprising: an outer hollow tubular sensor casing, a first end of which is open and a second end of which is closed and is provided with a protuberance for screw connection to the body;   an inner casing assembly inserted into said outer hollow tubular sensor casing through said open end, comprising a substantially air-tight container structure completely housed in a hollow space of said outer hollow tubular sensor casing, a cover plate portion spaced from said container structure so as to provide an intermediate space therebetween and closing said open end of said outer hollow tubular sensor casing, and a connector protecting shell portion extending outwardly from said cover plate portion through said open end of said outer hollow tubular sensor casing and providing a cavity space;   a vibration sensor element for producing an electrical signal, mounted within said container structure;   an electrically conducting lead wire having an inner end portion connected to said vibration sensor element for receiving a sensor output electrical signal therefrom and an outer end portion passing substantially air-tightly through a wall portion of said container structure to the outside thereof; and,   an electrical connector element extending through said cover plate portion towards said cavity space provided by said connector protecting shell portion and connected at a root end portion thereof located on the side of said cover plate portion remote from said connector protecting shell portion and located in said intermediate space with said outer end portion of said lead wire.   
     
     
       17. A sensor according to claim 16, wherein said container structure comprises a bottom plate element positioned in contact with said closed end of said outer hollow tubular sensor casing, a top plate element spaced from and confronting said bottom plate element, and a tubular side element positioned between said bottom plate element and said top plate element, said bottom, top and side elements being assembled as said substantially air-tight container structure when said inner casing assembly has been mounted to said outer hollow tubular sensor casing. 
     
     
       18. A sensor according to claim 16, wherein said container structure comprises a cup-shaped element and a plate element which closes an open end of said cup-shaped element. 
     
     
       19. A sensor according to claim 16, wherein said root end portion of said electrical connector element is mechanically fixed to said container structure together with said outer end portion of said lead wire. 
     
     
       20. A sensor according to claim 16, wherein said inner casing assembly is totally firmly assembled to said outer hollow tubular sensor casing by an edge portion of said open end of said outer hollow tubular sensor casing being clamped over said cover plate portion of said inner casing assembly.